1. Technical Field
The present invention relates to an image processing apparatus, an image processing method and a non-transitory computer readable medium.
2. Related Art
The correction of a digital image is generally performed using information such as, for example, luminance, chromaticity and frequency. The luminance emphasizes a pattern by brightening or darkening an image as a whole as compared to original brightness thereof or providing an intensity difference (contrast) to the image. In addition, with regard to the chromaticity, the image with a clear color is reproduced by chroma emphasis or correction of over-dyeing that shifts the color (color balance correction).
In some cases, the luminance and the chroma both may be adjusted. FIG. 10 is an explanatory view illustrating an example of the comparative correction processing. In FIG. 10, reference numeral 21 indicates a color conversion unit, reference numeral 22 indicates a luminance adjusting unit, reference numeral 23 indicates a chroma adjusting unit, and reference numeral 24 indicates a color conversion unit. A color image to be corrected which is captured by an imaging device such as, for example, a digital camera is represented by an RGB signal (primary color signal) such as, for example, an sRGB, herein. First, the RGB signal is converted into a luminance signal Y and a chromaticity signal CbCr in the color conversion unit 21. Next, the luminance signal is adjusted in the luminance adjusting unit 22 to be a luminance signal Y′. The adjustment of the luminance emphasizes the outline of, for example, a subject by a correction based on a tone curve or a correction of luminance frequency (band) information with a luminance image, thereby reproducing the detailed part that represents the pattern. Further, the chromaticity signal CbCr is subjected to chroma adjustment in the chroma adjusting unit 23 to be a chromaticity signal Cb′Cr′. The luminance signal Y′ adjusted in the luminance adjusting unit 22 and the chromaticity signal Cb′Cr′ adjusted in the chroma adjusting unit 23 are returned into an RGB signal R′G′B′ in the color conversion unit 24. Such a processing is performed for every pixel of the given color image to obtained a color image after adjustment.